A sodium-sulfur battery (NaS battery) operates at a high temperature. Therefore, in the NaS battery, electric cells, a heater, and the like are housed inside a container (heat-insulating container), and the temperature of the inside of the container is maintained at a high temperature, as shown in Patent Document 1. However, as mentioned in Paragraph 0010 of Patent Document 1, it is not preferable that the temperature of the inside of the container excessively rises, and therefore heat is exhausted from the inside of the container to the outside as necessary.
On the other hand, in a power storage apparatus (power storage compensation apparatus) provided with a NaS battery, a battery (module battery) in which electric cells are housed inside a container is sometimes further housed in an unsealed container (package), as shown in Patent Document 2. Heat exhausted from the inside of the container to the outside is exhausted from the inside of the unsealed container to the outside by an air flow that passes inside the unsealed container.
As mentioned in Paragraph 0037 of Patent Document 2, in a case where the power storage apparatus is installed in an area where salt damage may occur, a salt-resistant filter is installed on an intake port of the unsealed container in order to prevent salt damage.